Effects of dietary polyunsaturated fa tty acids , phospholipids on the survival and growth of Chinese cr ab , Er iocheir sinensis , f rom the megalopoa to the juvenile wer e studied using purif ied diets .The result shows that the sur vival of E .sinensis juvenile is gre atly incre ased by addit ion of the soybean phospholipids .But the sur vival to III juvenile is not significantly changed by only addit ion of the PUFA (C20∶5 +C22∶6 =58 . 5 %), except somewhat incre asing the sur vival from megalopa to the I juvenile .Mor eover , the composi tion of the unsatur ated f atty acids of the juvenile seems to vary significantly with the die tary level .